[lldb-vscode] Consistently use return EXIT_SUCCESS and EXIT_FAILURE (NFC)

[JDevlieghere]

Summary

Consistently use return with EXIT_SUCCESS or EXIT_FAILURE instead of mix-and-matching return, exit 0, 1 etc.

lldb/tools/lldb-vscode/lldb-vscode.cpp

if (llvm::opt::Arg *comm_file = input_args.getLastArg(OPT_comm_file)) {
           target_args_pos = i + 1;
           break;
         }
       LaunchRunInTerminalTarget(*target_arg, comm_file->getValue(),
                                 argv + target_args_pos);
     } else {
       llvm::errs() << "\"--launch-target\" requires \"--comm-file\" to be "
                       "specified\n";
-      exit(EXIT_FAILURE);
+      return EXIT_FAILURE;
     }
   }
 
   // Initialize LLDB first before we do anything.
   lldb::SBDebugger::Initialize();
 
   RegisterRequestCallbacks();
 
   int portno = -1;
 
   if (input_args.hasArg(OPT_help)) {
     printHelp(T, llvm::sys::path::filename(argv[0]));
-    return 0;
+    return EXIT_SUCCESS;
   }
 
   if (auto *arg = input_args.getLastArg(OPT_port)) {
     auto optarg = arg->getValue();
     char *remainder;
     portno = strtol(optarg, &remainder, 0);
     if (remainder == optarg || *remainder != '\0') {
       fprintf(stderr, "'%s' is not a valid port number.\n", optarg);
-      exit(1);
+      return EXIT_FAILURE;
     }
   }
 
 #if !defined(_WIN32)
   if (input_args.hasArg(OPT_wait_for_debugger)) {
     printf("Paused waiting for debugger to attach (pid = %i)...\n", getpid());
     pause();
   }
 #endif
   if (portno != -1) {
     printf("Listening on port %i...\n", portno);
     SOCKET socket_fd = AcceptConnection(portno);
     if (socket_fd >= 0) {
       g_vsc.input.descriptor = StreamDescriptor::from_socket(socket_fd, true);
       g_vsc.output.descriptor = StreamDescriptor::from_socket(socket_fd, false);
     } else {
-      exit(1);
+      return EXIT_FAILURE;
     }
   } else {
     g_vsc.input.descriptor = StreamDescriptor::from_file(fileno(stdin), false);
     g_vsc.output.descriptor =
         StreamDescriptor::from_file(fileno(stdout), false);
   }
   uint32_t packet_idx = 0;
   while (!g_vsc.sent_terminated_event) {
     llvm::json::Object object;
     lldb_vscode::PacketStatus status = g_vsc.GetNextObject(object);
     if (status == lldb_vscode::PacketStatus::EndOfFile)
       break;
     if (status != lldb_vscode::PacketStatus::Success)
       return 1; // Fatal error
 
     if (!g_vsc.HandleObject(object))
       return 1;
     ++packet_idx;
   }
 
   // We must terminate the debugger in a thread before the C++ destructor
   // chain messes everything up.
   lldb::SBDebugger::Terminate();
-  return 0;
+  return EXIT_SUCCESS;
 }